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This paper presents a vector data access method in memory, aimed at improve the I/O performance bottleneck in spatial data analysis. It uses memory copy instead of data interaction between disk and memory, as the memory copy operation is much faster than disk. It designs the vector spatial data model in memory as K-V structure, and presents the data access method between memory and SIC type. The experiment...
Vector map overlay is a core operation in the fields of spatial information processing. To meet the demand of overlay analysis with large scale vector data, this paper proposes a vector map overlay algorithm based on distributed task queue and designs a desirable task structure composed of geometries pair and a task assignment strategy based on spatial location. As well known, data access and load...
This paper concentrates on reducing the cost of I/O and improving algorithm efficiency by designing and realizing a spatial data access system based on main memory database (MMDB). We use Redis to manage vector spatial data in main memory which is faster than hard disk or disk-based database in respect of data access. We design a management strategy of spatial data, internal and external data exchange...
Based on the principle of the proximity of spatial elements and the equilibrium of spatial data's size, this paper presents a data partitioning and merging method based on spatial filling curve and collection of spatial features. In the data reducing section, this method takes the principle of dynamic tree merging and reduces the times of data serialization and deserialization. The experiment shows...
With the rapid growth of users and data volume, the state-of-the-art remotely sensed databases have been posed on grand challenges by the online geospatial applications. They cannot provide low-latency retrieval of big remotely sensed data and fail to adapt for various access patterns from concurrent users. We propose an adaptive hierarchical caching scheme called RSCache for remotely sensed database...
Interpolation is one time consuming and serial operation in the fields of spatial information processing. While fast processing speed is often required in some real-time interactive scenarios. With the development of Purpose computing on Graphics Processing Units (GPGPU), it provides an opportunity to accelerate some traditional inefficient algorithms with low-cost and low-power compared to clusters...
This paper proposes to design and realize a parallel strategy based on plane sweep algorithm that can be used in the multi-core system. The main contribution of this work is to present an efficient method to compute the large and complex data with plane sweep method. We use MPI (Message Passing Interface) as the programming model in Linux multi-core system, select shape file as the standard input...
Spatial co-location pattern mining means to find subsets of events whose instances are frequently located together in geographic space. Due to the complexity of spatial data types and spatial relationships, co-location mining is much more difficult than traditional transactions mining [1]. With the increasing of the amount of spatial data, computing time it costs grows sharply. In this paper, we present...
With the prevalence of data-intensive geospatial applications, massive spatio-temporal sensor data are obtained and the big data have posed grand challenges on existing index methods based on spatial databases due to their intrinsic poor scalability and retrieval efficiency. Motivated by the deficiencies, in this paper, we propose a distributed composite spatio-temporal index scheme called VegaIndexer...
With the emergence of online geospatial applications such as WebGIS services, the large spatio-temporal data and numerous concurrent users have posed grand challenges on the state-of-the-art spatial databases due to their intolerable disk I/O latency. Hence, the clients cannot be served with real-time response. In this paper, we propose VegaCache, a distributed inmemory caching scheme, to provide...
River generalization is an important part of Geographic Information System. Traditional research is focused on how to extract river systems of electronic maps correctly. They just delete rivers with low levels while not regarding redundant points of rivers of electronic maps or whether the speed of their methods could meet the users' demands. In this paper, we propose a method which filters out redundant...
With the increasing popularity of Geographic web services, quality of service (QoS) has become more and more important for the purpose of web service selection and composition. Conventional quality evaluation models just focus on the attributes which are expressed by exact, numerical values. However, some quality attributes are related to the subjective feeling of human beings, which is preferable...
The algorithm of line segment intersection is the core algorithm for vector map overlay. The traditional method is based on the plane-sweep process to find the intersections of two groups of lines. Although such method proves to be efficient in serial system, the basic data structure of this kind of algorithm needs to maintain a tree structure, which has the data-lock in multi-core system. In addition,...
Record-replay is effective to reproduce non-deterministic bugs, and has gained attentions in research community. However, current approaches fall short of handling nondeterministic bugs in multi-processor platforms and distributed systems due to several reasons. First, multi-thread programs on multi-processor platforms, which are common in today's distributed systems, are difficult to be recorded...
Anomaly detection is essential in network security. It has been researched for decades. Many anomaly detection methods have been proposed. Because of the simplicity of principles, statistical and Markovian methods dominate these approaches. However, their effectiveness is constrained by specific preconditions, which make them work for only appropriate data sets which satisfy their premises. Other...
With the rapid growth of geospatial data and concurrent users, the state-of-the-art WebGIS cannot support massive data storage and processing due to poor scalability of underlying centralized systems (e.g., native file systems and SDBMS). In this paper, we propose a novel distributed geospatial data storage and processing framework for large-scale WebGIS. Our proposal contains three significant characteristics...
In recent years, spatial applications have become more and more important in both scientific research and industry. Spatial query processing is the fundamental functioning component to support spatial applications. However, the state-of-the-art techniques of spatial query processing are facing significant challenges as the data expand and user accesses increase. In this paper we propose and implement...
Map projection is a key task in cartography that transforms the geographical coordinates from one coordinate system to another. It has been widely used in the Geographic Information System application. However, map projection is a very time-consuming task, and fast processing speed is often required in interactive GIS scenarios. Parallel computation provides an opportunity to reduce run times. Nowadays,...
The increase of storage and computing performance in embedded mobile platforms has provided better opportunities for the development of portable GPS software receiver. However, due to a large number of complex calculations in baseband operations, the real-time software receiver is still the biggest challenge, and in the baseband operations of the receiver, the largest time-consuming part is the satellite...
The software GPS receiver puts forward higher request for sensitivity and real-time processing. Due to a great quantity of complex calculations in the baseband operations, it consumes too much time to achieve real-time goal. In this paper, we propose an optimized method utilizing the DSP module as a support tool, converting most of the float calculations into integer calculations and reducing part...
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